'Son in law' in the Bible

David said to Saul, “Who am I, and what is my life or my father’s family in Israel, that I should be the king’s son-in-law?”

Saul said, “I will give her to him so that she may become a snare (bad influence, source of trouble) to him, and that the hand of the Philistines may be against him.” So Saul said to David for a second time, “You shall be my son-in-law today.”

Then Saul commanded his servants, “Speak to David secretly, saying, ‘Listen, the king delights in you, and all his servants love you; now then, become the king’s son-in-law.’”

So Saul’s servants spoke these words to David. But David said, “Is it a trivial thing in your sight to become a king’s son-in-law, seeing that I am a poor man and insignificant?”

When his servants told David these words, it pleased him to become the king’s son-in-law. Before the time [for the marriage] arrived,

David arose and went, he and his men, and killed two hundred Philistine men, and David brought their foreskins [as proof of death] and presented every one of them to the king, so that he might become the king’s son-in-law. So Saul gave him Michal, his [younger] daughter, as a wife.

Then Ahimelech answered the king, “And who among all your servants is as faithful and trustworthy as David, who is the king’s son-in-law, and who is captain over your guard [and your confidant], and is honored in your house?